Signal-responsive gating of porous membranes by polymer brushes

Abstract

Various types of signal-responsive polymers were grafted on surfaces of porous membranes as polymer brushes. The grafted polymers shrank and extended in response to environmental signals, such as pH, ionic strength, temperature, redox reaction and photo-irradiation. The pore size was regulated by the extent of the polymer brush. The phenomenon was observed in situ by atomic force microscopy. As a result, the substance permeation through the porous membrane was controlled in response to the signals. The permeation control was rapid in comparison with hydrogel-type membranes, and was reversibly performed. Copyright (C) 2000 John Wiley & Sons Ltd.